Method of purifying oils



l c. ALEXANDER. METHOD OF PURIFYING OILS.

APPLICATION FILED OCT. 1;"1'917- I Patented Jan. 10,1922.

2 $HEETSSHEET 1.

C. M. ALEXANDER.

METHOD OF PURIFYING OILSL APPLICATION FILED OCT-1. 1917.

Patented Jan. 10, 1922.

2 $HEETS-SHEET 2.

ways not necessary here to describe.

CLIVE M. ALEXANDER, OF PORT ARTHUR, TEXAS, ASSIGNOR T0 GULF REFINING- COM- IPA'NY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF nrrrrnon or rortrryme o-ILs.

Specification of Letters Patent.- Patented J 10; 1922.

Application filed October 1, 1917. Serial No. 194,199.

line, wherein the oil is mechanically agitated in a flowing current with a small proportionof sulfuric acid under temperature con trolled conditions; in the case of the treatment of cracked gasoline this sulfuric acid treatment being followed by a neutralizing treatment in the same manner and a subsequent steam distillation; and it also comprises certain combinations of apparatus elements adapted for use in the described process; all as more fully hereinafter set forth and as claimed. 1

In the purification of mineral oil it is the general practice to use sulfuric acid'at some stage in the operation. Ordinarily rather large amounts of sulfuric acid are employed and the oil and the acid are kept mingled and agitated by the use ofan air blast. The function of the sulfuric acid in the purification of the oils is not wholly understood, but it appears in large part to reside, in the usual methods of operation, in a combination of the sulfuric acid with various unsaturated bodies and aromatic bodies present; these reactive bodies being removed y the acid. In part the result seems to be the formation of sulfonic acids and other sulfur compounds. After. the treatment with sulfuric acid the acid is allowed to settle and the oil is washed with alkalis and water. The sludge acid is treated in various The oil treated with the acid has its color and burning qualities improved and it is also freed of various detrimental impurities.

One of the common ways of making an artificial gasoline today is the subjection of high boiling oils of various kinds, such as gas oil, solar oil, crudeoil, etc.-, to a high heat, the high heat being frequently accompanied by pressure. The oil may be treated in the liquid form or the vapor form as the case may be. The action of the heat is to break down the high boiling oil intolower boillng fractions; these fractions having to a greater or less extent the right boiling bustion engines but does affect their commercial quality and price considerably. These cracked, unsaturated gasolines are frequently quite yellow and the color tends to increase on standing. It is not practicable to treat these gasolines with sulfuric acid in the usual way for a number of reasons. n One, and the most important, is that since much of the oil is unsaturated, the action of the sulfuric acid in the usual way would cause too much of a loss of material; the shrinkage of the oil after an exhaustive treatment with sulfuric acid is too great; and too much sulfuric acid is also required. For

another thing, treatment with sulfuric acid and agitation by means of an air blast causes too much of a loss of vapor with these highly volatile asolines. Also, since the difference in speci c gravity of sulfuric acid and light gasoline is very great there are mechanical difliculties in securing a thorough and complete intermingling of the acid and oil where the two-are treated as large bodies by air blowing.

I have discovered that I can treat these gasolines with sulfuric acid without the noted great loss of oil or the use of great quantities of acid, producing an important improvement in their character; and notably in the removal of the yellow color. In so doing in the case of cracked gasoline I employ .a process consisting of several successive steps, one of these steps being a special treatment with sulfuric acid. This particular. treatment with sulfuric acid however is applicable to other oils than gasoline and in the description and claims hereinafter following vention. shall hereinafter therefore more I I wish it to be understood that as regards this step of my invenspecifically. describe its application to a like and convey the two therethrough under constant-agitation. The conduit I may provide with means for controlling its tempera ture; of abstracting the heat of reaction.

7 Under these circumstances and with a small proportion of sulfuric acid of 90 per cent or higher strength, say about 5 pounds or less to the barrel, the action appears to be more of an oxidation of certain constituents than a direct union with, or polymerization of,the unsaturated bodies present. I have found that I can replace the sulfuric acid in this treatment with/ various other oxidizing agents orI can lessen the weight of sulfuric acid required by dissolving in it oxidizing materials such as potassium or sodium bichromate. As little as one per cent of acid is effective for the present purposes but I i advantageously use somewhat more. The oil Baum solution of caustic soda per barrel is, an advantageous quantity. After the treat-' and the acid are caused to travel through the stated mixing conduit for a time and are then deposited in a settling columntoseparate. The gasoline is then passed in a similarway through a conduit together with a little caustic soda. A quarter gallon of 30 ment with the caustic soda, the gasoline is allowed to settle as before and is thensent to a still where it is distilled with theaid of steam. If desired, the alkali may be placed in the steam still and the intermediate passage of oil andalkali through a mixing conduit omitted; but I find it more advantageous to proceed as described. If alkal zation is done in the steam still, milk of lime may be used in lieu of caustic soda.

Asstated, the action of sulfuric acid in the present invention appears to be more of an oxidation than any action upon the unsaturated bodies.

oil is. otherwise improved but the unsaturated bodies are not removed. There is no great loss of oil; and the whole process may be conducted with 95 per cent recovery of amount which can be again reduced to half by using alittle bichromate'or other'oxidizing salt in connection with the acid. The amount of acid usedbeing very small the amount of acid sludge formed is also of course little; and as a matter of fact most of the' products formed by the acid in this;

operation appear to be oil soluble so'that there is very little sludge in any event.

invention.

The color is removed and the In treating oils with small amounts of acid in the present invention the size ofthe conduit through which they travel should be ample enough to give considerable free space above the normal liquid level in order to insure thorough agitation and mutual contact of the two liquids. While I have described kerosene or to other oils, such as lubricating oils, where it is desired to produce merely a decolorizing and purifying action without the substantial loss of oil occurring in the usual treatment with sulfuric acid.

In the accompanying drawings I have shown more or less diagrammatically one form of apparatus capable of performing the process and within the purview of my In these drawings- Figure '1 is a front elevation of the aparatus, various structural elements, such as cams, brace rods and stay wires and work mens platforms being omitted for simplicity of illustration;

Figure 2 is an end elevation taken to the left of Figure 1;

Figure 3 is a vertical section along line 33 of Figure 1 taken in the direction of the arrows.

Referring to the drawings 1 indicates beams of suitable character embedded in the foundation of concrete 2 and supporting the several elements of the complete apparatus as hereinafter described. Mounted upon the cross beam 3 is a'tank 4 in which the sulfuric acid is stored, and from which it is distributed. This tank is provided with a gage 5. Leading from the bottom of the tank is a pipe v6 which serves to conduct the sulfuric acid into the pipe 7 where it is joined by the gasoline delivered from a pump (not shown) through pipe 8. The gasoline and oil are the process. as used with cracked gasoline, it 1 is ofcourse equally applicable to cracked.

containing mixing blades 10 mounted on.

shaft 11 .(see Fig. 3). Stationary blades or lugs 11 may be mounted on the casing to cooperate with the rotary blades of the shaft. The shaft is journaled at 12 and driven by gear 13 actuated by chain 14 from pinion 15. This pinion is mounted on a shaft driven by'gear 16, chain 17 andvpinion 18, actuation being by motor 19. Suitable reduction gear between the motor and the latter pinion is indicated by 20.

The oil andthe sulfuric acid are mixed and conveyed through the mixing casing 9 and find exit through theTpipe 21, provided with swingable level adjusting device 21'.

In order to secure the best results the castrolled by this device. The mixture goes by pipe 22 to the tall vertical separator 23. The action of the oil andsulfuric acid on each other will of course develop heat and therefore it may be advantageous to control the temperature in the mixing casing by means of a spray device 24 supplied with cold water through pipe 25. The sprayed water is collected in the trough 26. The acid settles tothe bottom of theseparator 23, whence it may be drawn ofl', either continuously or intermittently, through pipe 27 and cock 28. The gasoline by-passes through connection 29 at a higher level and ascends through another leg, 30, of the separator, gage 31 being provided on this second leg for observation purposes. LAny acid settling in this second leg'joins that from the first leg. From the leg 30 the gasv oline is conducted through pipe 32 to a seca leading upwar 0nd conveyer and agitator 33, advantageously made of less length than the first mixing casing (9) but of similar construction. To this ipeis connected a pipe 33' lily and receiving alkali solution or ly-e from pipe 34' leading from tank 35. The lye tank may be of-similar construction to the sulfuric acid tank (4) and,

like it, is mounted on the platform 3 upon I-beams 36. It is provided with a ga e 37. The mixing casing 33 receives and de ivers a mixture of lye and gasoline, together with any separated matters, through pipe 38 to those of the mixin a separator 39. Another valved pipe, 40, 1s provided to permit tapping sediment collecting in the bottom of the mixing casing directly to this separator. The structure ofthe lye separator is similar to that of the separator 23. It is provided'with a by-pass 40. at a-point well above its bottom through which clarified and settled gasoline may I flowto theleg 41. Alkali solution and any impurities settle to the bottom of the sep-- arator and'may be drawn ofi' "either continuously or from time to time, through pipe 42 and cook 43. A gage 44'is provided to enable observation of the treated gasoline.

The mixing casing for thelye wash is provided with agitating means similar to casing for the acid treatment. Motion 1s imparted by pulley v45 on shaft 11 and chain 46, drivenby pinion 47 Under certain conditions, as hereinbefore explained, a special lye treatment may be dispensed with, inwhich event the stirrer ofthe lye treater may be thrown out; of action through the clutch mechanism shown, more or less diagrammatically, at-

48. Both the sulfuric acid and l e separators may be provided with ad itional draw-cits 49 and 50, respectively, for test-- purposes.

%he operation of the structure is obviousfrom the foregoing description and the drawing. It will be noted that the process.

is a continuous one in the sens-e that there is a constant feed of gasoline to be purified to the apparatus and withdrawal of purlfied gasoline to the stills. This purifiedgasoline leaves the purifying apparatus through pipe 60 whence it may be taken to a steam still (not shown).

In a specific embodiment of the present invention, using the apparatus described, I pass cracked gasoline into the mixing casing .soda solution and the gasoline are agitated together in 33 and pass into 39 and 41 where the caustic soda solution settles to the bottom, the gasoline passingto exit at 60. It may be taken by 60 to asteam still (not shown) and distilled with the aid of steam. Or, as stated, the acid treated mixture may be taken directly from 30 to a steam still (not shown) and there distilled in the presence of a little lime.

The proportions and strengths of acid and alkali stated givegood results, but both are susceptible of variation. For example, by using a somewhat stronger soda lye, say, one of 45 Baume and putting a little 'so a or lime in the still, a weaker acid, say one of 85 per cent, may be employed in the acid treatment.

But little acid sludge is formed in the present invention, most of the excess of acid going into the wash water; and there is a correspondingly small loss of oil.

recovered will of course depend upon the amount present; but in all cases the loss of oil inthe action is very little. In cracking oils, the nature ofthe product depends on the manufacturing methods; and the prodnot delivered by the condensers may all, or substantially all, beof such a nature as regards boiling points that it will rank com-- mercially as a motor fuel or gasoline; or it In treat-- ing' a cracked 011, the amount of gasoline.

[9. With it I introduce sulfuric acid of 90 may be, say, 50 per cent gasoline and 50 per cent burning oils. In applying the present method to sucha cracking oil condensate,

naturally only half the product recovered in the steam still will be gasoline. 7

But with ordinary cracked gasoline about 95 per cent of material of about the same gravity can berecovered as a distillate from the steam stills; the remaining 5 per cent being made up of, say, one per cent loss and say, 4 per cent heavy residues not distilled over in the steamstill in making the gasoline cut. *Use of weaker acids than about 98 per cent in the treatment results in a) greater loss of gasoline.

The color of the gasoline recov'eredin the present method depends to some extent on the strength of acid used. For a high 'degree of decolorization, stro'nger'acid is necessary than for lower degrees.

What I claim is: Y

1. In the purification of oils, theprocess which comprises transmitting an oil to be purified together with a small proportion of sulfuric acid as a continuously flowing stream through a temperature controlled conduit under mechanical agitation, the amount of acid being merely sufficient to oxidize unsaturated bodies with improvement of color without any substantial re- 'moval of hydrocarbons or polymerization thereof.

2. In the decolorization of cracked gasoline, the process which comprises conveying such a cracked gasoline together with a small amount of sulfuric acid as a continuously flowing stream through a temperature controlled conduit under mechanical agitation.

3. In the purification and decolorization of cracked gasoline, the process which comprises conveying such cracked gasoline together with a small, amount of sulfuric acid as a continuously flowing stream through a temperature controlled conduit under mechanical agitation, contacting the gasoline withalkali and steam distilling.

4. In the purification and decolorization of cracked gasoline, the process which comprlses conveylng such; cracked gasoline together with a small amount of sulfuric acid as a continuously. flowing stream through a temperature controlled conduit under mechanical agitation, contacting said gasoline with caustic soda solution in suflicient amount to remove-remaining acid and then steam distilling the neutral zed gasoline.

'5. In the purification anddecolorization of cracked gasoline, the process which com prises conveying such gasoline together with a little sulfuric acid as a continuously flowing stream through a temperature controlled conduit under mechanical agitation, there-' after passing the gasoline through a temperature controlled conduit in a similar manner in contact with a caustic sodasolu- "tion and steam distilling the gasoline so treated.

6. In the purification of petroleum oils containing unsaturated bodies, the process which comprises contacting with such petroleum oils, as a flowing stream through a temperature controlled conduit and under mechanical agitation not substantially more than 5 ounds sulfuric acid tothe barrel of oil, to lmprove the color without any substantial lossv of the hydrocarbons or polymerization thereof.

7. In the purification of oils, the process which comprises transmitting an oil to be gasoline together with a small proportion of I sulfuric acid into and through a horizontal tubular closed conduitand there vigorously agitating the gasoline and acid together,

such conduit being maintained only partially filled with the mixture of gasoline and acid flowing therethrough.

In testimony whereof, afiix my ture.

' CLIVE M. ALEXANDER. 

